This study explores the possibility of reconstructing the weather of Southeast Asia for the last decades using an atmospheric regional climate model, the Climate version of the Lokal-Modell (CLM). For this purpose global National Centers for Environmental Prediction–National Center for Atmospheric Research (NCEP–NCAR) reanalyses data were dynami...

This study explores the possibility of reconstructing the weather of Southeast Asia for the last decades using an atmospheric regional climate model, the Climate version of the Lokal-Modell (CLM). For this purpose global National Centers for Environmental Prediction–National Center for Atmospheric Research (NCEP–NCAR) reanalyses data were dynamically downscaled to 50 km and in a double-nesting approach to 18-km grid distance. To prevent the regional model from deviating significantly from the reanalyses with respect to large-scale circulation and large-scale weather phenomena, a spectral nudging technique was used. The performance of this technique in dealing with Southeast Asian typhoons is now examined by considering an ensemble of one simulated typhoon case. This analysis is new insofar as it deals with simulations done in the climate mode (so that any skill of reproducing the typhoon is not related to details of initial conditions), is done in ensemble mode (the same development is described by several simulations), and is done with a spectral nudging constraint (so that the observed large-scale state is enforced in the model domain). This case indicates that tropical storms that are coarsely described by the reanalyses are correctly identified and tracked; considerably deeper core pressure and higher wind speeds are simulated compared to the driving reanalyses. When the regional atmospheric model is run without spectral nudging, significant intraensemble variability occurs; also additional, nonobserved typhoons form. Thus, the insufficiency of lateral boundary conditions alone for determining the details of the dynamic developments in the interior becomes very clear. The same lateral boundary conditions are consistent with different developments in the interior. Several sensitivity experiments were performed concerning varied grid distances, different initial starting dates of the simulations, and changed spectral nudging parameters. Minimize

Recognizing that adaptation to both current and projected climate variability and change is best undertaken locally and regionally, a recent workshop was convened to analyze how regional climate services are delivered. Regional climate service organizations facilitate efficient adaptation by interacting with local and regional stakeholders. Regi...

Recognizing that adaptation to both current and projected climate variability and change is best undertaken locally and regionally, a recent workshop was convened to analyze how regional climate services are delivered. Regional climate service organizations facilitate efficient adaptation by interacting with local and regional stakeholders. Regional and local contextualization of observed and projected climate change is an important issue in large federally organized countries like Canada and Germany (as opposed to centralized countries). Exchanging knowledge and knowledge needs on changing climate regimes takes place in societal context within which scientific knowledge is challenged by various interest- led knowledge claims about climate change and its societal significance. Minimize

Climate impacts and adaptation research increasingly uses ensembles of regional and local climate change scenarios. To do so, the ensembles are examined to evaluate whether they describe a systematic difference between present states (and impacts) and envisaged future states—and such differences are often characterized as being statistically sig...

Climate impacts and adaptation research increasingly uses ensembles of regional and local climate change scenarios. To do so, the ensembles are examined to evaluate whether they describe a systematic difference between present states (and impacts) and envisaged future states—and such differences are often characterized as being statistically significant. This term “significance” is well defined by statistical terminology as the result of a test of a null hypothesis that is applied to samples of observations that are obtained with a defined sampling strategy. However such a statistical null hypothesis may not be a well-posed problem in the context of the evaluation of climate change scenarios. Therefore, the usage of terms such “statistically significant scenario” may be misunderstood in the general discourse about the certainty of projected climate change. We propose to employ instead a simple descriptive approach for characterizing the information in an ensemble of scenarios. Physical plausibility in the light of theoretical reasoning often adds robustness to the interpretation of climate change scenarios. Minimize

The6-hourly 1948–2010NCEP 1 reanalyses have been dynamically downscaled for the region of theNorth Pacific.With a detectingand- tracking algorithm, the climatology of North Pacific Polar Lows has been constructed. This derived climatology is consistent with the limited observational evidence in terms of frequency and spatial distribution. The cl...

The6-hourly 1948–2010NCEP 1 reanalyses have been dynamically downscaled for the region of theNorth Pacific.With a detectingand- tracking algorithm, the climatology of North Pacific Polar Lows has been constructed. This derived climatology is consistent with the limited observational evidence in terms of frequency and spatial distribution. The climatology exhibits strong year-to-year variability but weak decadal variability and a small positive trend. A canonical correlation analysis describes the conditioning of the formation of Polar Lows by characteristic seasonal mean flow regimes, which favor, or limit, cold air outbreaks and upper air troughs. Minimize